Improvement in ventilating-caps



' J. H IRWIN.

. vwnnmme-cu.

No.173,958. Patented Feb. 22, 1876.

fiinewes: jaw/i071 75, mob flak w, WM

7 improved cap with closed top.

UNITED STATES PATENT OFFICE.

JOHN H. IRWIN, on PHILADELPHIA, PENNSYLVANIA."

IMPROVEMENT IN VENTlLATING-CAPS.

Specification forming part of Letters Patent No. I 73,958, dated February 22, 1876; appiication filed July 23, 1875.

- edges inclined and parallel with the other deflecting-plates of the series.

That others may fully understand my invention, I will particularly describe it, having reference to the accompanying drawing, in

which- Figures 1 and 2 represent in elevation my A is the. pipe or flue through which a current of air is to be caused to'flow, and the otfice ot' the cap is to compel said flow by the atmospheric currents outside of said pipe or flue acting against the deflecting-surfaces of said cap, and the problem has been to effect this result with certainty in whatever direction the atmospheric currents may strike said cap.

In my patent dated May 19,1874, and numbered 150,958, I describe the principle of operation of the cap described herein,and reference is hereby made to the specification and drawings of said patent for a full exhibition of said principles.

'the large inclined plates shown in my said patent, and thereby wind is prevented from blowing down the flue when the air-currents are moving with a downward inclination.

Heretofore, when plates have beenemplloyed to close the flue-opening to prevent the entrance of descending currents of air, said plates have been elevated sufficiently far above said flue to permit the clear passage of a horizontal The plate 0 is exactly equal in diameter to the plate I), and is attached to the flue A, as shown clearly..

The relative arrangement of the deflectingplates of my cap is such that the apex of the one plate is about on the plane of the base of I the plate above it.

It will appear evident that, in Whatever di-' rection a current of air may encounter the plates at b c, it will enter the central space with an upward deflection, and pass across said space in that direction, the efiec't whereof will be a partial exhaustion of the air within. the flue A and the establishment of an upward flow therein.

Having described myinvention, whatIclaim as new is- The upper plate a, made horizontal over a space equal to the cross-sectional area of the flue, and having its edges turned downward, in combination withfthe plates be, said plates being so arranged in relation to each other that the base of one shall be on the plane of the apex of the other, and their inclined portions parallel, substantially as set forth.

JOHN H. IRWIN.

Witnesses:

GHAs. F. R. HENOKEROTH, REBECGA J. ELDER. 

